JP4853751B2

JP4853751B2 - Manufacturing method of electronic parts with excellent plating film thickness uniformity

Info

Publication number: JP4853751B2
Application number: JP2001037002A
Authority: JP
Inventors: 建一荒木; 文丈谷口; 伸一和井; 直樹松井; 光司佐藤
Original assignee: Hitachi Metals Ltd
Current assignee: Proterial Ltd
Priority date: 2001-02-14
Filing date: 2001-02-14
Publication date: 2012-01-11
Anticipated expiration: 2021-02-14
Also published as: JP2002246262A

Description

【発明の属する技術分野】
【０００１】
本発明は、セラミック基体に下地層と、当該下地層の表面に電解めっきで形成される導体層を有する外部電極を備えた電子部品とその製造方法に関し、特にはめっき膜厚均一性に優れた電子部品とその製造方法に関するものである。
【０００２】
【従来の技術】
近年、携帯電話に代表される移動体通信等の高周波機器の発展と普及に伴い、誘電体セラミックを基体としたチップコンデンサやＬＣフィルタ等の電子部品が急激に普及するようになった。これらの電子部品はＡｇ，Ｃｕ等からなる外部電極を有しているが、電子部品を回路基板に実装半田付けする際に、Ａｇでは溶融半田に溶解して外部電極が痩せて行く、いわゆる「はんだ食われ」という問題が生じる。そこで、ニッケル、ニッケル−Ｐ合金の導体層をバリア層として前記下地層の表面に形成するのが一般である。またＣｕはＡｇと比較すると溶融半田に対する溶解度は小さいが、信頼性の観点から同様にニッケル等のバリア層を形成することが行われているが、前記ニッケル、ニッケル−Ｐ合金、Ｃｕ等は溶融半田をよく濡らすことが出来ず、必要な半田付け強度が得られないため、「半田濡れ性」を高めるために更にＳｎ又はＳｎ−Ｐｂからなる半田をめっきすることが一般的に行われている。これら導体層はバレル浴を用いた電解めっき法により形成される場合が多いが、外部電極にめっきするにはセラミックは導通性が無いため、ダミーボールと呼ばれる金属球と電子部品をバレルに混合装入して同時にめっき液に浸漬し、前記金属球を介在して外部電極に通電している。
【０００３】
ところで、このような外部電極を形成した電子部品のひとつとして、図１に示すように、コンデンサ、伝送線路を内蔵したセラミック基板にダイオード、チップコンデンサ、チップ抵抗を搭載した複合電子部品１００が提案されている。
【０００４】
【発明が解決しようとする課題】
前記複合電子部品１００の外部電極は直流的に図２に破線で示すように接続され、例えば外部電極１は他の外部電極１２，１４，１６，Ｉ，Ｍ，Ｎ，Ｐと直流的に接続し、外部電極２は外部電極Ｋと接続する。このように、一つの電子部品において外部電極間の接続状態は一様ではない。その結果、めっきの際に外部電極に通電する役目を担う金属球との接触確率が各外部端子で異なることとなり、外部端子間でめっき膜厚のばらつきが生じる。
また前記金属球は、溶融した金属を油中に滴下したり線材を加熱し油中に投入することにより作成されることが多いが、このような製造方法で作られた金属球は直径のばらつきが大きいものが多い。このような直径バラツキが大きく、直径の大きな物を含有している金属球をダミーボールとして用いると、ダミーボールと外部電極との接触がスムーズに行われなくなり、めっき膜形成が遅くなり、膜厚ばらつきの大きなめっき膜が形成されるのを助長する。
また、金属球としては鉄ボールにニッケルめっきを施した物が多く用いられていが、このようなダミーボールではニッケルめっき被膜のピンホールから、鉄などの金属がめっき液中に溶けだしめっき液を汚染してしまい、溶け出した金属がめっき皮膜中に共析して、外部電極への正常なめっき被膜の形成を妨げる。
【０００５】
「はんだ食われ」を防ぐのにニッケル、ニッケル−Ｐ合金の導体層を前記下地層の表面に形成してバリア層として機能させるには、少なくとも１μｍ以上の膜厚が必要となる。一方ニッケル、ニッケル−Ｐ合金めっき膜は下地層に圧縮又は引張応力を作用させるために、めっき膜が厚くなると下地層のセラミック基体との密着強度を減少させたりするが、前記電子部品では膜厚を１０μｍ以下とすればよいことが、本発明者等が種々検討を行う中で明らかになっている。しかしながら、前記のように一つの電子部品において外部電極のめっき膜厚が大きくばらつくため、めっき膜厚を１μｍ以上１０μｍ以下とすることが困難であった。
また、「半田濡れ性」を高めるように前記導体層にＳｎを含有するめっき層を表面層として具備する場合には、その膜厚が３μｍ未満であると導体層を形成する金属とＳｎとが不動体合金膜を形成して、所望の半田濡れ性を得ることが出来ない。したがって、めっき処理時間を適宜調整して３μｍ以上のめっき膜厚を得ようとすれば、必然的にめっき工程時間が増加してしまうという問題があった。
そこで本発明の目的は、めっき膜厚均一性に優れた電子部品とその製造方法を提供することである。
【０００６】
【課題を解決するための手段】
本発明は、セラミック基体に複数の外部電極を有し、前記外部電極間の接続状態が複数の形態を有する電子部品の製造方法であって、前記外部電極はセラミック基体に形成される下地層と、当該下地層の表面に電解めっきで形成される導体層からなり、前記導体層をバレルめっきにより形成し、前記セラミック基体と混合装入する金属球として、均一液滴噴霧法で作製した平均粒径が０．１ｍｍ〜０．４８ｍｍの金属球を用い、前記金属球はＳｎを主成分とし、前記金属球由来のＦｅによるめっき浴の汚染が無いことを特徴とするめっき膜厚均一性に優れた電子部品の製造方法である。
前記金属球の直径の標準偏差は０．０５ｍｍ以下であることが好ましい。
また本発明は、前記導体層として、ニッケルめっき浴にて下地層の表面に膜厚の標準偏差が１．１μｍ以下のニッケルめっき膜を形成し、半田めっき浴にて前記ニッケルめっき膜上に膜厚の標準偏差が３．４μｍ以下の半田めっき膜を形成するめっき膜厚均一性に優れた電子部品の製造方法である。
【０００７】
【発明の実施の形態】
本発明の電子部品の製造方法においては、セラミック基体に形成された下地層の表面に形成される導体層を電解めっきで形成するが、その際に、バレルにセラミック基体と混合装入するダミーボールの直径を０．１mm〜１．０mmとしている。０．１mm 未満であるとダミーボール同士の間隙にめっき液が染みこまず正常な被膜が形成されず、また取り扱いも困難である。ダミーボール直径が１．０mmよりも大きいと外部電極への接触頻度が低下し被膜の形成が遅く、また膜厚のバラツキの大きな膜が形成される。また、ここで使用するダミーボールの粒径分布の標準偏差を０．２mm以内としている。標準偏差０．２ｍｍ超だと、それぞれの外部電極の電流密度分布にばらつきが生じ、均一なめっき膜を形成することが困難となる。この様にダミーボールは直径が小さく、その直径バラツキの小さなダミーボールを使うことで、膜厚のバラツキが小さくなり、前記導体層の膜厚の分布における標準偏差が１５μｍ以下としためっき膜厚均一性に優れた電子部品を得ることが出来る。
また、前記の粒径・粒径分布の標準偏差を有するダミーボールとして均一液滴噴霧（UDS）法で作製したＳｎを主成分とする金属球を用いた。この方法によれば、前記金属球の直径の分布における標準偏差が０．０５ｍｍ以下という、ばらつきの小さな金属球を得ることが出来る。このダミーボールを用いることで、Ｆｅを主成分とするダミーボールの様にめっき被膜を形成して異種金属の溶けだしを防ぐ必要が無くコスト的に優位である。まためっき浴に異種の金属が溶けだし、浴不純物として作用し正常な被膜形成を妨げられる事が無くなる。ダミーボールの素材としては例えば、外部電極にＳｎを主成分とするめっきを施す場合はＳｎを主成分とすることが望ましい。具体的な合金元素としては、Ag, Cu, Bi, Zn等の元素が例として挙げられる。
【０００８】
【実施例】
（実施例１）
本発明について一実施例を示し説明する。
まず、アルミナを主成分とするセラミックグリーンシートを作製した。そして、このセラミックグリーンシートの表面に、主にＡｇを主成分とする電極用ペーストをスクリーン印刷法により印刷して内部電極を形成した。印刷パターンの異なる内部電極を形成したセラミックグリーンシートを複数枚数積層して圧着し、積層体ブロックを得た。この積層体ブロックを積層方向に切断し、チップ状の積層体を作製した。このチップ状の積層体を、空気中で９００℃にて１時間焼成して、セラミック基体とした。その後、側面に内部電極が露出するようにバレル研磨を行い、続いてセラミック基体の側面、上面にＡｇを主成分とする下地層を形成して、内部電極と電気的に接続させた。この下地層上に直径の平均粒径が０．４８mm、標準偏差０．０２mmのSnを主成分としたダミーボールを用いて、ワット浴成分のニッケルめっき浴で、電解めっきを行いニッケルめっき膜を形成した。
なおニッケルめっき条件は次の通りである。
ダミ−ボール４kgと作成した試料２５００個を秤量の後、めっき用バレル容器に投入した。バレル容器内には電気的導通を確保するための電極が設けられている。この、製品とダミーボールを投入したバレル容器を前記のめっき液中に浸漬し、５ｒｐｍの速度で回転させた。また、同時に０．３A/dm²の電流を１００分間印可することによりニッケルめっきを行い、その後、水洗を行った。
以上により作製した電子部品を１０００個抜き取り、その全外部端子のニッケルめっき膜厚について蛍光Ｘ線膜厚計（セイコーインスツルメンツ社製、型式ＳＦＴ３０００）により測定し、膜厚の最大値、最小値、バラツキの標準偏差を評価した。
（実施例２）
また他の実施例として、ダミーボールを直径の平均粒径を０．３１mm、標準偏差０．０２mmのSnを主成分としたダミーボールとして、ワット浴成分のニッケルめっき浴で、電解めっきを行いニッケルめっき膜を形成した。他の条件、評価は実施例１と同一なのでその説明を省く。
（比較例１）
セラミック基体の側面、上面に形成したＡｇを主成分とする下地層上に、直径の平均粒径が１．５mm、標準偏差０．６５mmのＦｅを主成分とし、表面にニッケルめっきを施したダミーボールを用いて、ワット浴成分のニッケルめっき浴で、電解めっきを行いニッケルめっき膜を形成した。他の条件、評価は実施例１と同一なのでその説明を省く。
【００９】
上記ニッケルめっき膜厚の評価、めっき浴中のＦｅ濃度について表１に示す。
【００１０】
【表１】

【００１１】
本実施例のごとく、めっきを施した場合のニッケルめっき膜厚の標準偏差は、０．７μｍ〜１．１μｍであり、１μｍ以下１０μｍ以上のめっき膜厚の端子は全くなかった。一方、比較例の場合では、ニッケルめっき膜厚の標準偏差が３．７μｍであり、１μｍ以下めっき膜厚が１．１％、１０μｍ以上のめっき膜厚が１．７％発生した。
（実施例３）
実施例１と同様にして作成したニッケルめっき膜上に、直径の平均粒径が０．４８mm、標準偏差０．０２mmのSnを主成分としたダミーボールを用いて、半田めっき膜を形成した。なお半田めっき浴は不純物であるFeが0.01ppm以下で、外部端子にスズと鉛が９：１で析出する浴を使用した。
なお半田めっき条件は次の通りである。
ダミ−ボール４kgと作成した試料２５００個を秤量の後、めっき用バレル容器に投入した。バレル容器内には電気的導通を確保するための電極が設けられている。この、製品とダミーボールを投入したバレル容器を前記のめっき液中に浸漬し、５ｒｐｍの速度で回転させた。また、同時に０．３A/dm²の電流を１００分間印可することにより半田めっきを行い、その後、水洗を行った。
半田めっき膜厚についてもニッケルめっき同様測定し、膜厚の最大値、最小値、バラツキの標準偏差を評価した。また半田めっき後、外部電極を形成したセラミック基体を２２０℃の溶融した半田に３秒浸漬した後、端子の外観を拡大鏡にて観察し、半田濡れ性を評価した。また、１０万個の半田めっきが終了した後の、半田めっき液中の成分分析を行った。
（実施例４）
また他の実施例として、ダミーボールを直径の平均粒径を０．３１mm、標準偏差０．０２mmのSnを主成分としたダミーボールとして半田めっき膜を形成した。他の条件、評価は実施例３と同一なのでその説明を省く。
（比較例２）
ダミーボールを直径の平均粒径を１．５mm、標準偏差０．６５mmのＦｅを主成分とし、表面にニッケルめっきを施したダミーボールを用いてダミーボールとして半田めっき膜を形成した。他の条件、評価は実施例３と同一なのでその説明を省く。
【００１２】
上記半田めっき膜厚の評価、半田濡れ性の評価、めっき浴中のＦｅ濃度について表２に示す。
【００１３】
【表２】

【００１４】
本実施例のごとく、めっきを施した場合の半田めっき膜厚の標準偏差は、２．１〜３．４μｍであり、３μｍ以下のめっき膜厚の端子は全くなく、半田濡れ性不良の発生はなかった。また、ニッケルめっき後にニッケルめっき浴中の異種不純物であるFeは検出されなかった。一方、比較例のものでは半田めっき膜厚の標準偏差が16.7μｍであり、３μｍ以下のめっき膜厚の外部端子が35％発生し、半田濡れ性不良が１１％発生した。まためっき液中の異種不純物であるＦｅ濃度は121ppm増加した。
【００１５】
【発明の効果】
本発明によれば、めっき膜厚均一性に優れた電子部品とその製造方法を提供することできる。
【図面の簡単な説明】
【図１】本発明の一実施例に係る電子部品である。
【図２】本発明の一実施例に係る電子部品の外部電極接続図である。
【符号の説明】
１，２，３，４，５，６，７，８，９，１０，１１，１２，１３，１４，１５，１６外部端子
Ａ，Ｂ，Ｃ，Ｄ，Ｅ，Ｆ，Ｇ，Ｈ，Ｉ，Ｊ，Ｋ，Ｌ，Ｍ，Ｎ，Ｏ，Ｐ外部端子BACKGROUND OF THE INVENTION
[0001]
The present invention relates to an electronic component including an external electrode having a base layer on a ceramic substrate and a conductor layer formed on the surface of the base layer by electrolytic plating, and a method for manufacturing the same. The present invention relates to an electronic component and a manufacturing method thereof.
[0002]
[Prior art]
In recent years, electronic components such as chip capacitors and LC filters based on dielectric ceramics have rapidly spread with the development and popularization of high-frequency devices such as mobile communications typified by mobile phones. These electronic components have external electrodes made of Ag, Cu or the like, but when the electronic components are mounted and soldered to the circuit board, Ag dissolves in the molten solder and the external electrodes become thin. The problem of solder erosion occurs. Therefore, it is common to form a nickel or nickel-P alloy conductor layer on the surface of the underlayer as a barrier layer. Further, although Cu has a lower solubility in molten solder than Ag, a barrier layer such as nickel is similarly formed from the viewpoint of reliability. However, nickel, nickel-P alloy, Cu, etc. are melted. Since the solder cannot be wetted well and the required soldering strength cannot be obtained, it is generally performed to further solder with Sn or Sn—Pb in order to improve “solder wettability”. . These conductor layers are often formed by electrolytic plating using a barrel bath. However, ceramic is not conductive for plating external electrodes, so a metal ball called a dummy ball and electronic components are mixed in the barrel. At the same time, it is immersed in the plating solution, and the external electrodes are energized through the metal balls.
[0003]
By the way, as one of electronic components having such external electrodes formed, as shown in FIG. 1, a composite electronic component 100 in which a diode, a chip capacitor, and a chip resistor are mounted on a ceramic substrate incorporating a capacitor and a transmission line is proposed. ing.
[0004]
[Problems to be solved by the invention]
The external electrodes of the composite electronic component 100 are connected in a direct current as shown by broken lines in FIG. 2, for example, the external electrode 1 is connected in direct current to the other

external electrodes

12, 14, 16, I, M, N, and P. The external electrode 2 is connected to the external electrode K. Thus, in one electronic component, the connection state between the external electrodes is not uniform. As a result, the contact probability with the metal sphere that plays a role of energizing the external electrode during plating is different for each external terminal, resulting in variations in the plating film thickness between the external terminals.
In addition, the metal sphere is often made by dripping molten metal into oil or heating a wire rod into the oil, but the metal sphere made by such a manufacturing method has a variation in diameter. There are a lot of big ones. When a metal ball containing such a large diameter variation and containing a large diameter is used as a dummy ball, the contact between the dummy ball and the external electrode is not smoothly performed, and the plating film formation is slowed down. This facilitates the formation of a plating film with large variations.
In addition, many of the metal balls are made of iron balls with nickel plating. In such dummy balls, metal such as iron melts into the plating solution from the pinholes of the nickel plating film and contaminates the plating solution. As a result, the melted metal is co-deposited in the plating film, preventing the formation of a normal plating film on the external electrode.
[0005]
In order to prevent “solder erosion” and form a conductor layer of nickel or nickel-P alloy on the surface of the base layer to function as a barrier layer, a film thickness of at least 1 μm is required. On the other hand, since the nickel and nickel-P alloy plating film exerts compressive or tensile stress on the underlayer, the adhesion strength between the underlayer and the ceramic base decreases when the plating film becomes thick. It has been clarified that the present inventors have conducted various studies that it is sufficient to set the thickness to 10 μm or less. However, since the plating film thickness of the external electrode varies greatly in one electronic component as described above, it is difficult to set the plating film thickness to 1 μm or more and 10 μm or less.
Further, in the case where the conductor layer is provided with a plating layer containing Sn as a surface layer so as to enhance “solder wettability”, if the film thickness is less than 3 μm, the metal forming the conductor layer and Sn are formed. A desired alloy wettability cannot be obtained by forming an immobile alloy film. Therefore, if the plating process time is appropriately adjusted to obtain a plating film thickness of 3 μm or more, there is a problem that the plating process time inevitably increases.
Therefore, an object of the present invention is to provide an electronic component having excellent plating film thickness uniformity and a method for manufacturing the same.
[0006]
[Means for Solving the Problems]
The present invention is a method of manufacturing an electronic component having a plurality of external electrodes on a ceramic base, and the connection state between the external electrodes has a plurality of forms, wherein the external electrodes include a base layer formed on the ceramic base. An average particle produced by a uniform droplet spraying method as a metal sphere comprising a conductor layer formed by electrolytic plating on the surface of the underlayer, the conductor layer being formed by barrel plating, and mixed with the ceramic substrate. diameter have use a metal ball 0.1Mm～0.48Mm, said metal ball is mainly composed of Sn, the plating thickness uniformity, wherein a contamination of the plating bath according Fe from the metal ball is not This is an excellent method for manufacturing electronic components.
The standard deviation of the diameter of the metal ball is less der Rukoto preferably 0.05 mm.
According to the present invention, as the conductor layer, a nickel plating film having a standard deviation of a film thickness of 1.1 μm or less is formed on the surface of the underlayer using a nickel plating bath, and the film is formed on the nickel plating film using a solder plating bath. This is a method for manufacturing an electronic component excellent in plating film thickness uniformity for forming a solder plating film having a standard deviation of thickness of 3.4 μm or less.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the method of manufacturing an electronic component according to the present invention, a conductor layer formed on the surface of the base layer formed on the ceramic substrate is formed by electrolytic plating. At this time, a dummy ball is mixed and charged in the barrel with the ceramic substrate. The diameter is set to 0.1 mm to 1.0 mm. When the thickness is less than 0.1 mm, the plating solution does not penetrate into the gap between the dummy balls, a normal film is not formed, and handling is difficult. If the diameter of the dummy ball is larger than 1.0 mm, the frequency of contact with the external electrode decreases, the formation of the film is slow, and a film with a large variation in film thickness is formed. In addition, the standard deviation of the particle size distribution of the dummy balls used here is within 0.2 mm. If the standard deviation is more than 0.2 mm, the current density distribution of each external electrode varies and it becomes difficult to form a uniform plating film. In this way, the dummy ball has a small diameter, and by using a dummy ball having a small diameter variation, the variation in film thickness is reduced, and the standard deviation in the distribution of the film thickness of the conductor layer is 15 μm or less. An electronic component having excellent properties can be obtained.
Further, as a dummy ball having a standard deviation of the particle size and particle size distribution, a metal sphere mainly composed of Sn produced by a uniform droplet spraying (UDS) method was used. According to this method, it is possible to obtain a metal sphere having a small variation in which the standard deviation in the distribution of the diameter of the metal sphere is 0.05 mm or less. The use of this dummy ball is advantageous in terms of cost because it is not necessary to form a plating film as in the case of a dummy ball containing Fe as a main component to prevent melting of different metals. In addition, different types of metals start to dissolve in the plating bath and act as bath impurities, preventing normal film formation from being hindered. As a material for the dummy ball, for example, when plating the outer electrode with Sn as a main component, it is desirable to have Sn as a main component. Specific examples of alloy elements include elements such as Ag, Cu, Bi, and Zn.
[0008]
【Example】
Example 1
The present invention will be described with reference to an embodiment.
First, a ceramic green sheet mainly composed of alumina was produced. Then, an electrode paste mainly composed of Ag was printed on the surface of the ceramic green sheet by a screen printing method to form internal electrodes. A plurality of ceramic green sheets on which internal electrodes having different printing patterns were formed were laminated and pressure-bonded to obtain a laminate block. This laminated body block was cut | disconnected in the lamination direction, and the chip-shaped laminated body was produced. This chip-like laminate was fired in air at 900 ° C. for 1 hour to obtain a ceramic substrate. Thereafter, barrel polishing was performed so that the internal electrode was exposed on the side surface, and then a base layer containing Ag as a main component was formed on the side surface and the upper surface of the ceramic substrate, and was electrically connected to the internal electrode. Using a dummy ball mainly composed of Sn having an average diameter of 0.48 mm and a standard deviation of 0.02 mm on this underlayer, electrolytic plating is performed in a nickel plating bath of a watt bath component to form a nickel plating film. Formed.
The nickel plating conditions are as follows.
4 kg of dummy balls and 2500 prepared samples were weighed and placed in a plating barrel container. An electrode for ensuring electrical continuity is provided in the barrel container. The barrel container in which the product and the dummy ball were put was immersed in the plating solution and rotated at a speed of 5 rpm. At the same time, nickel plating was performed by applying a current of 0.3 A / dm ² for 100 minutes, followed by washing with water.
1000 electronic parts produced as described above were extracted, and the nickel plating film thickness of all the external terminals was measured with a fluorescent X-ray film thickness meter (model SFT3000, manufactured by Seiko Instruments Inc.), and the maximum value, minimum value, and variation of film thickness. The standard deviation of was evaluated.
(Example 2)
In another embodiment, the dummy ball is a dummy ball mainly composed of Sn having an average diameter of 0.31 mm and a standard deviation of 0.02 mm. A plating film was formed. Since other conditions and evaluation are the same as those in the first embodiment, the description thereof is omitted.
(Comparative Example 1)
A dummy mainly composed of Fe with an average particle diameter of 1.5 mm and a standard deviation of 0.65 mm on the side layer and upper surface of the ceramic substrate, which is mainly composed of Ag. Using a ball, electrolytic plating was performed in a nickel plating bath as a Watt bath component to form a nickel plating film. Since other conditions and evaluation are the same as those in the first embodiment, the description thereof is omitted.
[0109]
Table 1 shows the evaluation of the nickel plating film thickness and the Fe concentration in the plating bath.
[0010]
[Table 1]

[0011]
As in this example, the standard deviation of the nickel plating film thickness when plated was 0.7 μm to 1.1 μm, and there was no terminal having a plating film thickness of 1 μm or less and 10 μm or more. On the other hand, in the case of the comparative example, the standard deviation of the nickel plating film thickness was 3.7 μm, the plating film thickness of 1 μm or less was 1.1%, and the plating film thickness of 10 μm or more was 1.7%.
(Example 3)
A solder plating film was formed on the nickel plating film prepared in the same manner as in Example 1, using dummy balls mainly composed of Sn having an average diameter of 0.48 mm and a standard deviation of 0.02 mm. The solder plating bath used was a bath in which Fe, which is an impurity, was 0.01 ppm or less and tin and lead were precipitated at an external terminal at 9: 1.
The solder plating conditions are as follows.
4 kg of dummy balls and 2500 prepared samples were weighed and placed in a plating barrel container. An electrode for ensuring electrical continuity is provided in the barrel container. The barrel container in which the product and the dummy ball were put was immersed in the plating solution and rotated at a speed of 5 rpm. Simultaneously, solder plating was performed by applying a current of 0.3 A / dm ² for 100 minutes, followed by washing with water.
The solder plating film thickness was also measured in the same manner as the nickel plating, and the maximum value, minimum value, and standard deviation of the film thickness were evaluated. After solder plating, the ceramic substrate on which the external electrodes were formed was immersed in molten solder at 220 ° C. for 3 seconds, and then the appearance of the terminals was observed with a magnifying glass to evaluate solder wettability. In addition, the components in the solder plating solution were analyzed after the completion of 100,000 solder platings.
Example 4
As another example, a solder plating film was formed as a dummy ball composed mainly of Sn having an average diameter of 0.31 mm and a standard deviation of 0.02 mm. Since other conditions and evaluation are the same as those in Example 3, the description thereof is omitted.
(Comparative Example 2)
A solder plating film was formed as a dummy ball using a dummy ball having a dummy ball whose main component is Fe having an average diameter of 1.5 mm and a standard deviation of 0.65 mm and whose surface is nickel-plated. Since other conditions and evaluation are the same as those in Example 3, the description thereof is omitted.
[0012]
Table 2 shows the evaluation of the solder plating film thickness, the evaluation of solder wettability, and the Fe concentration in the plating bath.
[0013]
[Table 2]

[0014]
As in this example, the standard deviation of the solder plating film thickness when plating is 2.1 to 3.4 μm, there are no terminals with a plating film thickness of 3 μm or less, and the occurrence of poor solder wettability There wasn't. Further, Fe, which is a different impurity in the nickel plating bath, was not detected after nickel plating. On the other hand, in the comparative example, the standard deviation of the solder plating film thickness was 16.7 μm, 35% of the external terminals having a plating film thickness of 3 μm or less were generated, and 11% of the solder wettability defect was generated. Further, the Fe concentration, which is a different impurity in the plating solution, increased by 121 ppm.
[0015]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the electronic component excellent in plating film thickness uniformity and its manufacturing method can be provided.
[Brief description of the drawings]
FIG. 1 is an electronic component according to an embodiment of the present invention.
FIG. 2 is an external electrode connection diagram of an electronic component according to an embodiment of the present invention.
[Explanation of symbols]
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 External terminals A, B, C, D, E, F, G, H, I , J, K, L, M, N, O, P External terminal

Claims

A method of manufacturing an electronic component having a plurality of external electrodes on a ceramic substrate, wherein the connection state between the external electrodes has a plurality of forms,
The external electrode includes a base layer formed on a ceramic base and a conductor layer formed on the surface of the base layer by electrolytic plating. The metal is formed by barrel plating and mixed with the ceramic base. as spheres, an average particle size prepared in a uniform droplet spray method have use a metal ball 0.1Mm～0.48Mm,
The method for producing an electronic component having excellent plating film thickness uniformity , wherein the metal sphere comprises Sn as a main component and the plating bath is not contaminated by Fe derived from the metal sphere .

Method of manufacturing an electronic component excellent in plating thickness uniformity of claim 1 standard deviation of the diameter of the metal ball and wherein the Ru der below 0.05 mm.

As the conductor layer, a nickel plating film having a standard deviation of a film thickness of 1.1 μm or less is formed on the surface of the underlayer in a nickel plating bath, and the standard deviation of the film thickness is formed on the nickel plating film in a solder plating bath. The method for producing an electronic component having excellent plating film thickness uniformity according to claim 2, wherein a solder plating film of 3.4 μm or less is formed.